Posted: 11/03/2014 at 08:34
How to fill will depend to an extent on the size and depth of the pool and the material available. I filled in a large pond approx 18' x 6' x 2' deep by dumping the stone previously used for edging in the bottom along with any other rubble I could find for the bottom 12", topped that with soil from raised beds around the pool and soil from other areas of the garden where I wanted to change the levels.
Landgirl100 makes an important point about leaving the ground to settle. I actually did the work in the autumn and then left over 2 winters i.e. about 18 months before doing anything with it. That was to allow the soil time to be taken down around the stones. If you will completely with soil, 12 months should be fine.